Configuration OpenDNS in TomatoUSB firmware

Hello community,

 I try to use the extra services of OpenDNS (created an account) on my ASUS RT-N66U router with TomatoUSB firmware on it (Tomato Firmware 1.28.0000 MIPSR2-140 K26 USB AIO-64K). 

I also created an account at DNS-O-Matic (with the same credentials as OpenDNS) to follow this description in the article:

https://support.opendns.com/hc/en-us/community/posts/220007787-Tomato-DNS-O-Matic

Brian says : Due to how Tomato processes the URL you must use a username, not your email address.

My question is : What is my username???? (btw : It is NOT my DISPLAY name!)

Greetings, willem